A vertical tank of 4.sm2 cross-sectional area is filled with 13.5m3 of water, 9.0m3 0f a fluid with an s.G. of 3.2,6.75;. or oir with an s.G. of 0.85 and 0.9m3 of mercury with an s.G. of 13.s7. The fluids do not mix and the atmospheric pressure is 1.01 x 105 N/m2. Determine the gauge pressure head and the absolute pressure head in metres of water at i depth of 6.6m below the free surface.